1. Technical Field of the Invention
The present invention relates in general to the field of wireless communications, and in particular, to operating a satellite communications system in conjunction with optimized call routing.
2. Description of Related Art
Mobile wireless communication is becoming increasingly important for providing safety, convenience, improved productivity, and simple conversational pleasure to subscribers of wireless communications systems. One prominent mobile wireless communication option is cellular communication. Cellular phones, for instance, can be found in cars, briefcases, purses, and even pockets. With the proliferation of cellular phone use, cellular phone subscribers are demanding increased coverage areas as well as the ability to use their cellular phones across different geographical areas, types of wireless networks, wireless network service providers, etc. One way to increase the size and geographical diversity of coverage areas is to employ satellite communication systems. These satellite communication systems may be based on any of many traditional wireless communication network standards.
Referring now to FIG. 1 of the drawings, an exemplary cellular wireless communication network system, such as a Public Land Mobile Network (PLMN) 100 operating in accordance with the Global System for Mobile Communication (GSM) standard, is described. The PLMN 100 is composed of a plurality of areas 105, each with a Mobile Services Switching Center (MSC) 110 and an integrated Visitor Location Register (VLR) 115 therein. The MSC/VLR areas 105, in turn, include a plurality of Location Areas (LA) 120, which are defined as that part of a given MSC/VLR area 105 in which a Mobile Terminal (MT) 125 may move freely without having to send update location information to the MSC/VLR 110 that controls the LA 120. Each LA 120 is divided into a number of cells 130. The MT 125 is the physical equipment (e.g., a car phone, a computer with a wireless link, other portable phone, etc.) used by mobile subscribers to communicate with the cellular network 100, each other, and users outside the subscribed network, both wireline and wireless.
The MSC 110 is in communication with at least one Base Station Controller (BSC) 135, which, in turn, is in contact with at least one Base Transceiver Station (BTS) 140. The BTS 140 is the physical equipment, illustrated for simplicity as a radio tower, that provides radio coverage to the geographical part of the cell 130 for which it is responsible. It should be understood that the BSC 135 may be connected to several BTSs 140, and may be implemented as a stand-alone node or integrated with the MSC 110. In either event, the BSC 135 and the BTS 140 components, as a whole, are generally referred to as a Base Station System 145.
With further reference to FIG. 1, the PLMN Service Area or wireless network 100 includes a Home Location Register (HLR) 150, which is a database maintaining all subscriber information (e.g., user profiles, current location information, International Mobile Subscriber Identity (IMSI) numbers, other administrative information, etc.). The HLR 150 may be Column-located with a given MSC 110, integrated with the MSC 110, or alternatively can service multiple MSCs 110, the latter of which is illustrated in FIG. 1.
The VLR 115 is a database containing information about all of the MTs 125 currently located within the MSC/VLR area 105. If an MT 125 roams into a new MSC/VLR area 105, the VLR 115 connected to that MSC 110 will request data about that MT 125 from the HLR database 150 (simultaneously informing the HLR 150 about the current location of the MT 125). Accordingly, if the user of the MT 125 then wants to make a call, the local VLR 115 will have the requisite identification information without having to reinterrogate the HLR 150. In the aforedescribed manner, the VLR and HLR databases 115 and 150, respectively, contain various subscriber information associated with a given MT 125.
Referring now to FIG. 2, an exemplary satellite-based wireless network system with three transmission paths identified is illustrated generally at 200. The satellite-based wireless network system 200 indicates how the GSM standard may be incorporated into a general (e.g., regional) satellite-based wireless network system. An MT 125xe2x80x2 is in communication with an MT 125xe2x80x3 via a satellite 205. The satellite-based wireless network system 200 also includes a satellite Base Station Subsystem (BSS) 135xe2x80x2 connected to a satellite gateway 210, which is also connected to another satellite BSS 135xe2x80x3. The gateway 210 may include a Gateway MSC (GMSC) 215, an MSC 110, and a VLR 115. It should be noted that neither any two nor all of the GMSC 215, the MSC 110, and the VLR 115 need be located at the same geographical location and that the gateway 210 need not include any of them. A transmission 220, which is represented by a dotted line, shows a transmission path between the MT 125xe2x80x2 and the MT 125xe2x80x3 that does not include the MSC 110 (e.g., a single hop in the satellite-based wireless network system 200). On the other hand, a transmission 225, which is represented by a dashed line, shows a transmission path between the MT 125xe2x80x2 and the MT 125xe2x80x3 that does include the MSC 110 (e.g., a double hop in the satellite-based wireless network system 200).
Also in FIG. 2 (although not necessarily an integral part of the satellite-based wireless network system 200), a Public Switched Telephone Network (PSTN)/PLMN 230 is illustrated. The PSTN/PLMN 230 is in communication with wireline terminals 235 and wireless terminals 240 as well as the gateway 210. A transmission 245, which is represented by a dashed and dotted line, shows a transmission path between a wireline terminal 235 or a wireless terminal 240 and the MT 125xe2x80x3 from, or through, the PSTN/PLMN 230.
One of the principle benefits of satellite-based wireless network systems is the large geographic areas that may be covered by a single homogenous system. Consequently, these large coverage areas may span across long-distance zones or even the borders of one or more countries. Each of these satellite-based wireless network systems typically has more than one satellite gateway 210, each of which serves as a nexus between the particular satellite-based wireless network system and one or more external communication systems such as PSTNs, other PLMNs, the Internet, etc. The path through which a call is routed from a satellite subscriber (e.g., the satellite subscriber associated with the MT 125xe2x80x2) or an external subscriber (e.g., a subscriber associated with the wireline terminal 235 and/or the wireless terminal 240) to another satellite subscriber (e.g., the satellite subscriber associated with the MT 125xe2x80x3) usually traverses a gateway 210.
A satellite MT (e.g., the MT 125xe2x80x2 or the MT 125xe2x80x3) may be registered or re-registered (e.g., permanently or temporarily assigned within the satellite-based wireless network system 200) to a particular gateway 210, which then serves as the nexus through which the satellite MT sends and receives communications. The respective geographic location(s) of the gateway 210 of the satellite MT and a party (or their registered gateway 210) calling or being called by the satellite MT are therefore determinative of whether the call is of the long-distance or international variety, which usually cause the total cost of the call to escalate dramatically. When the gateway registration or re-registration process is effectuated without the knowledge of the associated satellite subscriber, the cost of calls becomes indeterminate and unpredictable from the perspective of the subscriber. This indeterminate and unpredictable cost condition is undesirable inasmuch as most subscribers are dissatisfied to discover unexpected charges on their service subscription invoices.
These indeterminate and unpredictable cost deficiencies of the prior art are overcome by the method and system of the present invention. For example, as heretofore unrecognized, it would be beneficial to optimize the completion of calls so as to prevent unexpected charges from appearing on the bills of satellite subscribers. In fact, it would be beneficial if incoming calls that would otherwise cause unexpected long distance/international charges to be incurred were completed so as to avoid such charges (e.g., by re-registering the incoming call).
The method and system of the present invention enable optimal call routing in a satellite communications network when a satellite subscriber has, for example, call forwarding, call transfer, etc. active. Many satellite networks will re-register a satellite subscriber (e.g., move the subscriber""s VLR data) to another satellite gateway that is more, if not the most, cost efficient when the satellite subscriber initiates a call. If the called party is distant from the satellite subscriber""s home country, the gateway to which the re-registration occurs is likely to be far from the gateway of his or her native country. Call forwarding, of course, is often directed to a number that is local to the satellite subscriber""s home country (e. c, the call forwarding is directed to work or to home).
As a result of, for example, a call forwarding activation in conjunction with a re-registration to a distant gateway upon the initiation of a call by the satellite subscriber, an incoming call to the satellite subscriber will cause unexpected charges to appear on the satellite subscriber""s bill absent application of the teachings of the present invention. In accordance with the principles of the present invention, however, any and all of several exemplary embodiments prevent the unexpected charges from appearing on the bill of the satellite subscriber.
For example, the satellite network may route the incoming call as if it originated within a PSTN/PLMN and thus suppress the normal re-registration of the other satellite subscriber that initiated the incoming call. Suppressing such re-registration results in the incoming call being routed as if it were a normal PSTN/PLMN call to the called satellite subscriber; this may trigger certain embodiments of the invention. Alternatively, satellite gateways and satellite control system (SCS) nodes may be modified such that they are able to re-register a calling satellite subscriber to the home/originating gateway of the called satellite subscriber. This re-registration in turn causes certain embodiments of the invention to be triggered in the most efficient manner. Additionally, the satellite network may communicate with one or more nodes in an Intelligent Network (IN), which is typically provided with adequate programming and data to determine a least expensive route and/or to calculate the cost of the expected/predicted routing. This charge is then applied to the bill of the subscriber of the satellite MT in lieu of long distance/international type charges.
The above-described and other features of the present invention are explained in detail hereinafter with reference to the illustrative examples shown in the accompanying drawings. Those skilled in the art will appreciate that the described embodiments are provided for purposes of illustration and understanding and that numerous equivalent embodiments are contemplated herein.